1. Field of the Invention
The invention relates to a back up recovery system used for a communication based train control (CBTC) system for determining the location, train identification numbers, and the total number of vehicles in the CBTC system.
2. Description of Related Art
Until recently, identifying the location of a train having one or more vehicles on a train track was an inexact science. The train track, or guideway, was divided into fixed sections known as blocks and once a particular train entered and occupied a block, no other trains could enter that block since the exact location of the occupying train was unknown within the occupied block.
The fixed blocks can vary in length from hundreds of feet to miles on a particular track. In many instances, this fixed block arrangement adversely affects a train""s schedule by preventing a train from entering a block, even though it is a safe distance from the next closest train that happens to be located in that block. Recently, the concept of moving blocks has been implemented within the automatic train protection (ATP) system of a CBTC system. A moving block system is a dynamic system which creates an imaginary space, or train envelope, that automatically moves along with a particular train as that train travels along a track such that no other train may enter that imaginary space. The length of the moving block depends on various characteristics, such as train speed, train acceleration/deceleration rates and braking ability. A simple example of a moving block is a train envelope which extends 100 feet in front of, and fewer feet behind a particular train. Exchange of data between the train and at least one wayside computer through regular train-to-wayside communication enables processors and controllers to determine the appropriate safe separation between trains. Safe train separation can be continuously calculated, and this separation defines the moving block that moves along with the train. The length of the moving block varies as the operating parameters of the train change.
While the moving block system is more efficient than the fixed block system, it is imperative in the moving block system that a train onboard computer communicates with one or more wayside computers to determine for each train at least the train identification number, the number of vehicles in the train configuration, the train location in the CBTC system, and the train speed. Based on the collected data from the trains, the wayside computers must be able to determine the total number of communicating trains within each region. In the event one or more trains stop communicating with the wayside computers, then critical information about those trains becomes unavailable, thereby causing the system to place a prohibit block or default train envelope around each non-communicating train. That results in time consuming remedial efforts to remove the default train envelope around each non-communicating train. Similar problems may exist, but on a bigger scale, when the prohibit blocks cover the entire system. This may occur during cold startup of primary and secondary wayside computers thus preventing all the trains from operating in an automatic mode. During a cold startup process, the wayside computers have no knowledge of the train identifications, locations, or their operating information.
In the past, for relatively fast recovery of the ATP system caused by one or more non-communicating trains, simultaneous multiple common mode failures or software failures, an underlay fixed type block system was implemented. This is a secondary (backup) system that works in the background, while the CBTC system is operating normally. Train detection mechanisms, such as track circuits, wheel detectors, and axle counters are the most common currently used technologies in these secondary systems. However, each of these require the installation of new equipment and such an undertaking may be expensive and time consuming to the point of reducing the benefits and time savings of the communication based train control system.
In the absence of these backup mechanisms, recovery of the moving block system may be costly and time consuming. Since the geographical system layout and size as well as the total number of operating trains have a direct proportional impact on the cost and recovery time, this is particularly significant for medium and large systems. One recovery method requires the wayside computers to poll all of the operating vehicles in the system based upon the last-known set of data prior to the system malfunction. However, it is entirely possible that during the course of this malfunction trains could be added, removed or relocated between a system main guideway and a yard (Maintenance and Storage Facility or MandSF) within the system, such that the memory of the wayside computers is entirely inaccurate. Under these circumstances, the central control operator would have to dispatch train operators to drive the affected trains in a manual sweep mode in which the speed limit is usually under 10 miles per hour, until all prohibit blocks placed by the system are removed as the manually driven trains traverse them. In a sense, this is like surveying the tracks in the entire system to identify the existence of vehicles and determine whether or not all the trains were indeed communicating with a wayside computer. If a vehicle/train was not communicating with a wayside computer, that vehicle must be removed from the system.
Furthermore, in order to accurately update the data in the wayside computer and reestablish communication between the communicating trains and wayside computers, it is necessary to move each communicating train past an initialization area using wayside sensors to detect train movements. However, since the wayside computers are not fully recovered, the system must operate in an unprotected, manual mode whereby the trains cannot be moved faster than 5-10 miles per hour until all segment blocks are cleared. Once all of the blocks have been cleared, the system is restored to full automatic operation. While this method is reliable, depending on the system size and number of recovered trains, it may take a number of hours and a large recovery crew to implement. As a result, the overall efficiency of the ATP system may be reduced.
A system is needed that, in the event of a wayside computer cold startup where it is necessary to detect non-communicating train movement within the blocks of a series of blocks defining a region, will promote recovery of an ATP system, in a timely fashion.
While a particular ATP system has been described, it should be appreciated there are many different types of ATP systems and expedited recovery of these ATP systems is needed in the event of a malfunction or failure of the ATP system.
One embodiment of the invention is directed to a train registry associated with a railway track system for providing detection of trains having vehicles within the system to assist in startup or failure recovery of an automated train protection subsystem in a communications based train control system. The track system has a main guideway and the train registry comprises:
a) a wayside computer for receiving and interpreting base data to determine at least i) the location, within one of a plurality of predefined zones within the system, of each train; ii) the identification of vehicles of each train within the system; and iii) the total number of trains in the system;
b) at least one transponder positioned on each train vehicle in the system, wherein each transponder contains at least the identification of the train vehicle with which it is associated; and
c) transponder readers positioned at a plurality of wayside locations, or registration points, along the guideway for polling the transponders on each train vehicle when they are proximate to the reader to determine the location and the identification of each train vehicle and to forward this base data to the wayside computer.
Another embodiment of the subject invention is directed to a method for streamlining startup or failure recovery of an automatic train protection subsystem in a communications based train control system for a railway track system having a track and trains with vehicles thereon. The method comprises the steps of:
a) positioning a plurality of transponder readers throughout the track system along the track;
b) mounting upon each train vehicle at least one transponder capable of providing to each reader the train vehicle identification;
c) moving each train vehicle past at least one transponder reader such that the train transponder transmits at least the train vehicle identification to the respective reader;
d) with the identification information for each train vehicle and the location of the transponder reader identifying each train vehicle, determining at least i) the location, within one of a plurality of predefined zones within the system, of each train; ii) the identification of each train vehicle within the system; and iii) the total number of train vehicles in the system; and
e) at the time of startup or failure recovery of the train protection system, providing base data including the identification of each train vehicle, the total number of train vehicles in each zone and the zone in which each train vehicle is located to the train protection subsystem, thereby providing initialization information to the train protection subsystem.